Linear Polarization Features in the Quiet-Sun Photosphere: Structure and Dynamics

Kianfar, Sepideh; Jafarzadeh, S.; Mirtorabi, Mohammad Taghi; Riethmüller, T. L.

doi:10.1007/s11207-018-1341-2

Cited by 12 publications

(13 citation statements)

References 62 publications

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“…The algorithm has been used in various fields, including solar physics (e.g. [49,50]). In this study, the TrackPy package is used to perform the tracking analysis.…”

Section: (A) Feature Detectionmentioning

confidence: 99%

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High-frequency oscillations in small chromospheric bright features observed with Atacama Large Millimetre/Submillimetre Array

Gómez

Jafarzadeh

Wedemeyer

et al. 2020

Phil. Trans. R. Soc. A.

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We report detection of oscillations in brightness temperature, size and horizontal velocity of three small bright features in the chromosphere of a plage/enhanced-network region. The observations, which were taken with high temporal resolution (i.e. 2 s cadence) with the Atacama large millimetre/ submillimetre array (ALMA) in Band 3 (centred at 3 mm; 100 GHz), exhibit three small-scale features with oscillatory behaviour with different, but overlapping, distributions of period on the order of, on average, 90 ± 22 s, 110 ± 12 s and 66 ± 23 s, respectively. We find anti-correlations between perturbations in brightness, temperature and size of the three features, which suggest the presence of fast sausage-mode waves in these small structures. In addition, the detection of transverse oscillations (although with a larger uncertainty) may also suggest the presence of Alfvénic oscillations which are likely representative of kink waves. This work demonstrates the diagnostic potential of high-cadence observations with ALMA for detecting high-frequency magnetohydrodynamic waves in the solar chromosphere. Such waves can potentially channel a vast amount of energy into the outer atmosphere of the Sun. This article is part of the Theo Murphy meeting issue ‘High-resolution wave dynamics in the lower solar atmosphere’.

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“…The algorithm has been used in various fields, including solar physics (e.g. [49,50]). In this study, the TrackPy package is used to perform the tracking analysis.…”

Section: (A) Feature Detectionmentioning

confidence: 99%

“…This algorithm has been implemented in Python for finding blob-like features in time series of images by means of the TrackPy package [49]. The algorithm has been used in various fields, including solar physics (e.g., [50,51]). In this study, the TrackPy package is used to perform the tracking analysis.…”

Section: (A) Feature Detectionmentioning

confidence: 99%

High-frequency oscillations in small chromospheric bright features observed with Atacama Large Millimetre/Submillimetre Array

Gómez

Jafarzadeh

Wedemeyer

et al. 2020

Phil. Trans. R. Soc. A.

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“…with Kianfar et al (2018) determining them to be short-lived (30 − 300 s), small structures with weak fields observed equally in up-flow and down-flow regions. Kaithakkal & Solanki (2019) found cancellation sites in the quiet Sun surrounding a young active region.…”

Section: Introductionmentioning

confidence: 99%

Temporal evolution of small-scale internetwork magnetic fields in the solar photosphere

Campbell

Mathioudakis

Collados

et al. 2021

A&A

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Context. While the longitudinal field that dominates in photospheric network regions has been studied extensively, small-scale transverse fields have recently been found to be ubiquitous in the quiet internetwork photosphere and this merits further study. Furthermore, few observations have been able to capture how this field evolves. Aims. We aim to statistically characterize the magnetic vector in a quiet Sun internetwork region and observe the temporal evolution of specific small-scale magnetic features. Methods. We present two high spatio-temporal resolution observations that reveal the dynamics of two disk-centre internetwork regions taken by the new GREGOR Infrared Spectrograph Integral Field Unit with the highly magnetically sensitive photospheric Fe I line pair at 15648.52 Å and 15652.87 Å. We record the full Stokes vector and apply inversions with the Stokes inversions based on response functions code to retrieve the parameters characterizing the atmosphere. We consider two inversion schemes: scheme 1 (S1), where a magnetic atmosphere is embedded in a field free medium, and scheme 2 (S2), with two magnetic models and a fixed 30% stray light component. Results. The magnetic properties produced from S1 inversions returned a median magnetic field strength of 200 and 240 G for the two datasets, respectively. We consider the median transverse (horizontal) component, among pixels with Stokes Q or U, and the median unsigned longitudinal (vertical) component, among pixels with Stokes V, above a noise threshold. We determined the former to be 263 G and 267 G, and the latter to be 131 G and 145 G, for the two datasets, respectively. Finally, we present three regions of interest, tracking the dynamics of small-scale magnetic features. We apply S1 and S2 inversions to specific profiles of interest and find that the latter produces better approximations when there is evidence of mixed polarities. We find patches of linear polarization with magnetic flux density of the order of 130−150 G and find that linear polarization appears preferentially at granule-intergranular lane boundaries. The weak magnetic field appears to be organized in terms of complex ‘loop-like’ structures, with transverse fields often flanked by opposite polarity longitudinal fields.

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“…The interaction between granules and magnetic fields is not completely clear and there are several scientific open questions on the involved processes, especially related to the emergence of magnetic flux concentrations at the granular spatial scale [ 30 , 31 , 32 ] and their subsequent diffusion [ 33 , 34 , 35 ]. In this context, some authors have highlighted the presence of ubiquitous horizontal fields in the internetwork [ 36 , 37 , 38 , 39 ]. Other authors have studied the evolution of coherent magnetic flux structures emerging in the quiet Sun.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Pseudo-Lyapunov Exponents of Solar Convection Using State-of-the-Art Observations

Viavattene

Murabito

Guglielmino

et al. 2021

Entropy

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The solar photosphere and the outer layer of the Sun’s interior are characterized by convective motions, which display a chaotic and turbulent character. In this work, we evaluated the pseudo-Lyapunov exponents of the overshooting convective motions observed on the Sun’s surface by using a method employed in the literature to estimate those exponents, as well as another technique deduced from their definition. We analyzed observations taken with state-of-the-art instruments at ground- and space-based telescopes, and we particularly benefited from the spectro-polarimetric data acquired with the Interferometric Bidimensional Spectrometer, the Crisp Imaging SpectroPolarimeter, and the Helioseismic and Magnetic Imager. Following previous studies in the literature, we computed maps of four quantities which were representative of the physical properties of solar plasma in each observation, and estimated the pseudo-Lyapunov exponents from the residuals between the values of the quantities computed at any point in the map and the mean of values over the whole map. In contrast to previous results reported in the literature, we found that the computed exponents hold negative values, which are typical of a dissipative regime, for all the quantities derived from our observations. The values of the estimated exponents increase with the spatial resolution of the data and are almost unaffected by small concentrations of magnetic field. Finally, we showed that similar results were also achieved by estimating the exponents from residuals between the values at each point in maps derived from observations taken at different times. The latter estimation technique better accounts for the definition of these exponents than the method employed in previous studies.

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Linear Polarization Features in the Quiet-Sun Photosphere: Structure and Dynamics

Cited by 12 publications

References 62 publications

High-frequency oscillations in small chromospheric bright features observed with Atacama Large Millimetre/Submillimetre Array

High-frequency oscillations in small chromospheric bright features observed with Atacama Large Millimetre/Submillimetre Array

Temporal evolution of small-scale internetwork magnetic fields in the solar photosphere

Analysis of Pseudo-Lyapunov Exponents of Solar Convection Using State-of-the-Art Observations

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